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NG_HCI(4)		 BSD Kernel Interfaces Manual		     NG_HCI(4)

NAME
     hci -- Netgraph node type that is also a Bluetooth	Host Controller	Inter-
     face (HCI)	layer

SYNOPSIS
     #include <sys/types.h>
     #include <netgraph/ng_message.h>
     #include <netgraph/netgraph.h>
     #include <netgraph/ng_hci.h>

DESCRIPTION
     The hci node type is a Netgraph node type that implements Bluetooth Host
     Controller	Interface (HCI)	layer as per chapter H1	of the Bluetooth Spec-
     ification Book v1.1.

INTRODUCTION TO	BLUETOOTH
     Bluetooth is a short-range	radio link intended to replace the cable(s)
     connecting	portable and/or	fixed electronic devices. Bluetooth operates
     in	the unlicensed ISM band	at 2.4 GHz. The	Bluetooth protocol uses	a com-
     bination of circuit and packet switching. Bluetooth can support an	asyn-
     chronous data channel, up to three	simultaneous synchronous voice chan-
     nels, or a	channel	which simultaneously supports asynchronous data	and
     synchronous voice.	Each voice channel supports a 64 kb/s synchronous
     (voice) channel in	each direction.	The asynchronous channel can support
     maximal 723.2 kb/s	asymmetric (and	still up to 57.6 kb/s in the return
     direction), or 433.9 kb/s symmetric.

     The Bluetooth system provides a point-to-point connection (only two Blue-
     tooth units involved), or a point-to-multipoint connection. In the	point-
     to-multipoint connection, the channel is shared among several Bluetooth
     units. Two	or more	units sharing the same channel form a piconet.	One
     Bluetooth unit acts as the	master of the piconet, whereas the other
     unit(s) acts as slave(s). Up to seven slaves can be active	in the pi-
     conet.  In	addition, many more slaves can remain locked to	the master in
     a so-called parked	state. These parked slaves cannot be active on the
     channel, but remain synchronized to the master. Both for active and
     parked slaves, the	channel	access is controlled by	the master.

     Multiple piconets with overlapping	coverage areas form a scatternet.
     Each piconet can only have	a single master. However, slaves can partici-
     pate in different piconets	on a time-division multiplex basis. In addi-
     tion, a master in one piconet can be a slave in another piconet. The pi-
     conets shall not be frequency-synchronized. Each piconet has its own hop-
     ping channel.

   Time	slots
     The channel is divided into time slots, each 625 usec in length. The time
     slots are numbered	according to the Bluetooth clock of the	piconet	mas-
     ter.  The slot numbering ranges from 0 to 2^27 -1 and is cyclic with a
     cycle length of 2^27. In the time slots, master and slave can transmit
     packets.

   SCO link
     The SCO link is a symmetric, point-to-point link between the master and a
     specific slave. The SCO link reserves slots and can therefore be consid-
     ered as a circuit-switched	connection between the master and the slave.
     The SCO link typically supports time-bounded information like voice. The
     master can	support	up to three SCO	links to the same slave	or to differ-
     ent slaves. A slave can support up	to three SCO links from	the same mas-
     ter, or two SCO links if the links	originate from different masters. SCO
     packets are never retransmitted.

   ACL link
     In	the slots not reserved for SCO links, the master can exchange packets
     with any slave on a per-slot basis. The ACL link provides a packet-
     switched connection between the master and	all active slaves participat-
     ing in the	piconet. Both asynchronous and isochronous services are	sup-
     ported. Between a master and a slave only a single	ACL link can exist.
     For most ACL packets, packet retransmission is applied to assure data in-
     tegrity.

HOST CONTROLLER	INTERFACE (HCI)
     The HCI provides a	command	interface to the baseband controller and link
     manager, and access to hardware status and	control	registers. This	inter-
     face provides a uniform method of accessing the Bluetooth baseband	capa-
     bilities.

     The HCI layer on the Host exchanges data and commands with	the HCI
     firmware on the Bluetooth hardware. The Host Controller Transport Layer
     (i.e. physical bus) driver	provides both HCI layers with the ability to
     exchange information with each other.

     The Host will receive asynchronous	notifications of HCI events indepen-
     dent of which Host	Controller Transport Layer is used. HCI	events are
     used for notifying	the Host when something	occurs.	When the Host discov-
     ers that an event has occurred it will then parse the received event
     packet to determine which event occurred.	The next sections specify the
     HCI packet	formats.

   HCI command packet
	   #define NG_HCI_CMD_PKT 0x01
	   typedef struct {
		   u_int8_t  type;   /*	MUST be	0x1 */
		   u_int16_t opcode; /*	OpCode */
		   u_int8_t  length; /*	parameter(s) length in bytes */
	   } __attribute__ ((packed)) ng_hci_cmd_pkt_t;

     The HCI command packet is used to send commands to	the Host Controller
     from the Host. When the Host Controller completes most of the commands, a
     Command Complete event is sent to the Host. Some commands do not receive
     a Command Complete	event when they	have been completed. Instead, when the
     Host Controller receives one of these commands the	Host Controller	sends
     a Command Status event back to the	Host when it has begun to execute the
     command. Later on,	when the actions associated with the command have fin-
     ished, an event that is associated	with the sent command will be sent by
     the Host Controller to the	Host.

   HCI event packet
	   #define NG_HCI_EVENT_PKT 0x04
	   typedef struct {
		   u_int8_t type;   /* MUST be 0x4 */
		   u_int8_t event;  /* event */
		   u_int8_t length; /* parameter(s) length in bytes */
	   } __attribute__ ((packed)) ng_hci_event_pkt_t;

     The HCI event packet is used by the Host Controller to notify the Host
     when events occur.

   HCI ACL data	packet
	   #define NG_HCI_ACL_DATA_PKT 0x02
	   typedef struct {
		   u_int8_t  type;	 /* MUST be 0x2	*/
		   u_int16_t con_handle; /* connection handle +	PB + BC	flags */
		   u_int16_t length;	 /* payload length in bytes */
	   } __attribute__ ((packed)) ng_hci_acldata_pkt_t;

     HCI ACL data packets are used to exchange ACL data	between	the Host and
     Host Controller.

   HCI SCO data	packet
	   #define NG_HCI_SCO_DATA_PKT 0x03
	   typedef struct {
		   u_int8_t  type;	 /* MUST be 0x3	*/
		   u_int16_t con_handle; /* connection handle +	reserved bits */
		   u_int8_t  length;	 /* payload length in bytes */
	   } __attribute__ ((packed)) ng_hci_scodata_pkt_t;

     HCI SCO data packets are used to exchange SCO data	between	the Host and
     Host Controller.

HCI INITIALIZATION
     On	initialization,	HCI control application	must issue the following HCI
     commands (in any order).

     Read_BD_ADDR
	     To	obtain BD_ADDR of the Bluetooth	unit.

     Read_Local_Supported_Features
	     To	obtain the list	of features supported by Bluetooth unit.

     Read_Buffer_Size
	     To	determine the maximum size of HCI ACL and SCO HCI data packets
	     (excluding	header)	that can be sent from the Host to the Host
	     Controller. There are also	two additional return parameters that
	     specify the total number of HCI ACL and SCO data packets that the
	     Host Controller can have waiting for transmission in its buffers.

     As	soon as	HCI initialization has been successfuly	performed, HCI control
     application must turn on "inited" bit for the node. Once HCI node has
     been initialized all upsteam hooks	will receive a NGM_HCI_NODE_UP Net-
     graph message defined as follows.

	   #define NGM_HCI_NODE_UP 112 /* HCI -> Upper */
	   typedef struct {
		   u_int16_t pkt_size; /* max. ACL/SCO packet size (w/o	hdr) */
		   u_int16_t num_pkts; /* ACL/SCO packet queue size */
		   u_int16_t reserved; /* place	holder */
		   bdaddr_t  bdaddr;   /* bdaddr */
	   } ng_hci_node_up_ep;

HCI FLOW CONTROL
     HCI layer performs	flow control on	baseband connection basis (i.e.	ACL
     and SCO link). Each baseband connection has connection handle and queue
     of	outgoing data packets. Upper layers protocols are allowed to send up
     to	( num_pkts - pending) packets at one time. HCI layer will send
     NGM_HCI_SYNC_CON_QUEUE Netgraph messages to inform	upper layers about
     current queue state for each connection handle. The
     NGM_HCI_SYNC_CON_QUEUE Netgraph message is	defined	as follows.

	   #define NGM_HCI_SYNC_CON_QUEUE 113 /* HCI ->	Upper */
	   typedef struct {
		   u_int16_t con_handle; /* connection handle */
		   u_int16_t completed;	 /* number of completed	packets	*/
	   } ng_hci_sync_con_queue_ep;

HOOKS
     This node type supports the following hooks:

     drv     Bluetooth Host Controller Transport Layer hook. Single HCI	packet
	     contained in single mbuf structure.

     acl     Upper layer protocol/node is connected to the hook. Single	HCI
	     ACL data packet contained in single mbuf structure.

     sco     Upper layer protocol/node is connected to the hook. Single	HCI
	     SCO data packet contained in single mbuf structure.

     raw     Raw hook. Every HCI frame (including HCI command frame) that goes
	     in	or out will be delivired to the	hook. Usually Bluetooth	raw
	     HCI sockets layer is connected to the hook. Single	HCI frame con-
	     tained in single mbuf structure.

BLUETOOTH UPPER	LAYER PROTOCOLS	INTERFACE (LP CONTROL MESSAGES)
     NGM_HCI_LP_CON_REQ
	  Requests the lower protocol to create	a connection. If a physical
	  link to the remote device does not exist, this message must be sent
	  to the lower protocol	(baseband) to establish	the physical connec-
	  tion.

     NGM_HCI_LP_DISCON_REQ
	  Requests the lower protocol (baseband) to terminate a	connection.

     NGM_HCI_LP_CON_CFM
	  Confirms success or failure of the NGM_HCI_LP_CON_REQ	request	to es-
	  tablish a lower layer	(baseband) connection.	This includes passing
	  the authentication challenge if authentication is required to	estab-
	  lish the physical link.

     NGM_HCI_LP_CON_IND
	  Indicates the	lower protocol (baseband) has successfully established
	  incoming connection.

     NGM_HCI_LP_CON_RSP
	  A response accepting or rejecting the	previous connection indication
	  request.

     NGM_HCI_LP_DISCON_IND
	  Indicates the	lower protocol (baseband) has terminated connection.
	  This could be	a response to NGM_HCI_LP_DISCON_REQ or a timeout
	  event.

     NGM_HCI_LP_QOS_REQ
	  Requests the lower protocol (baseband) to accommodate	a particular
	  QoS parameter	set.

     NGM_HCI_LP_QOS_CFM
	  Confirms success or failure of the request for a given quality of
	  service.

     NGM_HCI_LP_QOS_IND
	  Indicates the	lower protocol (baseband) has detected a violation of
	  the QoS agreement.

NETGRAPH CONTROL MESSAGES
     This node type supports the generic control messages, plus	the following:

     NGM_HCI_NODE_GET_STATE
	  Returns current state	for the	node.

     NGM_HCI_NODE_INIT
	  Turn on "inited" bit for the node.

     NGM_HCI_NODE_GET_DEBUG
	  Returns an integer containing	the current debug level	for the	node.

     NGM_HCI_NODE_SET_DEBUG
	  This command takes an	integer	argument and sets current debug	level
	  for the node.

     NGM_HCI_NODE_GET_BUFFER
	  Returns current state	of data	buffers.

     NGM_HCI_NODE_GET_BDADDR
	  Returns BD_ADDR as cached in the node.

     NGM_HCI_NODE_GET_FEATURES
	  Returns the list of features supported by hardware (as cached	by the
	  node).

     NGM_HCI_NODE_GET_NEIGHBOR_CACHE
	  Returns content of the neighbor cache.

     NGM_HCI_NODE_FLUSH_NEIGHBOR_CACHE
	  Remove all neighbor cache entries.

     NGM_HCI_NODE_GET_CON_LIST
	  Returns list of active baseband connections (i.e. ACL	and SCO
	  links).

     NGM_HCI_NODE_GET_STAT
	  Returns various statistic counters.

     NGM_HCI_NODE_RESET_STAT
	  Resets all statistic counters	to zero.

     NGM_HCI_NODE_SET_LINK_POLICY_SETTINGS_MASK
	  Sets current link policy settings mask. After	the new	ACL connection
	  is created the HCI node will try set link policy for the ACL connec-
	  tion.	By default every supported Link	Manager	(LM) mode will be en-
	  abled. User can override this	by setting link	policy settings	mask
	  which	specifies LM modes to be enabled.

     NGM_HCI_NODE_GET_LINK_POLICY_SETTINGS_MASK
	  Returns current link policy settings mask.

     NGM_HCI_NODE_SET_PACKET_MASK
	  Sets current packet mask. When new baseband (ACL or SCO) connection
	  is created the HCI node will specify every packet type supported by
	  the device.  User can	override this by setting packet	mask which
	  specifies packet types to be used for	new baseband connections.

     NGM_HCI_NODE_GET_PACKET_MASK
	  Returns current packet mask.

SHUTDOWN
     This node shuts down upon receipt of a NGM_SHUTDOWN control message, or
     when all hooks have been disconnected.

BUGS
     Most likely. Please report	if found.

SEE ALSO
     netgraph(4), ngctl(8), hccontrol(8)

HISTORY
     The hci node type was implemented in FreeBSD 5.0.

AUTHORS
     Maksim Yevmenkin <m_evmenkin@yahoo.com>

BSD				 June 25, 2002				   BSD

NAME | SYNOPSIS | DESCRIPTION | INTRODUCTION TO BLUETOOTH | HOST CONTROLLER INTERFACE (HCI) | HCI INITIALIZATION | HCI FLOW CONTROL | HOOKS | BLUETOOTH UPPER LAYER PROTOCOLS INTERFACE (LP CONTROL MESSAGES) | NETGRAPH CONTROL MESSAGES | SHUTDOWN | BUGS | SEE ALSO | HISTORY | AUTHORS

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